Expression of cell cycle–associated mRNAs during terminal erythroid differentiation.

Total RNA was isolated from FVA erythroblasts at the indicated times during differentiation. Gel electrophoresis was performed, and ethidium bromide-stained rRNA was photographed as a control for loading (A). Northern blot analysis was performed using radiolabeled cDNA probes to Friend retroviral components (B), β-globin (C), cdk2 (D), cdk4 (E), cyclin D3 (F), and p21 (G).